Plans to widen I-66 in Virginia outside of Washington, DC include building a new bike trail that runs from Dunn Loring all the way out to Centreville. It's great that a new trail is on the way, but if plans don't change, it's going to be dangerous and uninviting.

Interstate 66 will soon be wider between Haymarket and Falls Church. The current plans call for ten lanes (there are currently between six and eight), with the new road having three regular lanes and two High Occupancy Toll (HOT) Lanes in each direction.

Widening 66 isn't a great idea because that alone will not reduce congestion in Northern Virginia, but one positive aspect is that the project will include a new trail that effectively runs Gallows Road to Centreville (it'd go there at first, but then even farther).

The trail will help build out Fairfax County's bike network, providing connections to the W&OD trail, the Cross County Trail, and others. It will run to Gallows Road in Dunn Loring, near the W&OD. That connects to the Custis Trail, which runs parallel to I-66 in Arlington, and the result will effectively mean one of the longest trails in the region. A lot of local neighborhoods will have a new option for biking and walking as a result.

The Custis Trail is the red line , and I-66 is the thick grey line alongside it. VDOT plans to extend the Custis Trail along 66 out to Centreville. (Image by OpenStreetMap licensed under Creative Commons.)

It's nice to get new trails, but this one could be a lot better.

As it is currently planned, the new trail would put trail users in a squeeze, literally. Plans show it running along the highway side of the sound barrier, the big wall that separates 66 from where people live. That means trail users would be closer to high-speed traffic and farther from the neighborhood connections, which likely means far fewer people would be willing to get out and use it.

Walling the trail in between the sound barrier and highway could also lead to some congestion of its own, and prevent the trail from being expanded in the future (unlike the highway).

Air quality is another concern. Trail users would be exposed to more air pollution on the highway side of the wall and force users to breathe in all the extra exhaust coming from the traffic of a widened highway.

A better design would move the trail to the opposite side of the sound wall, and make it at least 12 feet wide. That would make it more accessible, more safe, more pleasant, and more practical as a transportation connection.

The Fairfax Alliance for Better Bicycling put together a short video showing what using a trail like this would look like. While the highway is huge, the path—meant to be shared by pedestrians and cyclists—would be quite small, with unwelcoming barriers on each side.

All in all, the current plan would lead to a substandard experience for trail users despite promises that a widened 66 would be a benefit for everybody, not just drivers.

We've been here before.

This isn't the first time residents of our region have been promised that big highway projects would come with equal bike, pedestrian, and transit accommodations only to get the short end of the stick.

Some of the compromises that were reached to build the Intercounty Connector in Maryland relied on new bus service and a trail. But the bus service was quickly cut while the road stayed, and while there is an ICC trail, it was rerouted and parts of it were cut out of "concern for the environment." Apparently, some places can handle a six lane highway but not a 12-foot wide trail.

Instances like this one make it seem like "multi-modal" is not so much about having different options for transportation as it is about saying the right things so people will sign off on a highway project where the details aren't too important.

We are seeing some of the same steps being taken here with VDOT. The road must be a certain width, and if that means that cyclists and pedestrians get short shrift then so be it. Then for future projects, the problems on the current trail will either be ignored or cited as evidence for why trails should not be held to the same design standards we have for highways. In other words, we can treat trail users badly because we have always treated them badly.

The pressure to widen 66 is very high, and VDOT wants to do it despite its own data saying the only way to keep congestion in check is through tolling and keeping non-driving options open. This political reality led advocates to at least push for better bus service and the new trail, and the new lanes will be tolled, but VDOT seems less concerned with working on actual solutions to congestion in Northern Virginia than it is with adding new highway lanes.

This trail could be so much better.

It doesn't have to be this way. It's not like building a trail next to a highway is an anomaly in the Washington area, so VDOT can't claim that they just don't know what is best when it comes to building a trail near a highway. As I mentioned earlier, the Custis Trail already runs alongside 66 inside the Beltway, and while its not a perfect trail, it's a good start to build on.

For a trail that could connect hundreds of thousands of people in dozens of neighborhoods, it is critical that we make sure we follow best practices and design trails that are well made, useful, and not just an afterthought meant to get the environmentalists off of VDOT's back.